The objective of this study is to determine by means of randomized controlled clinical trials whether argon laser photocoagulation is of benefit in preventing visual acuity loss in eyes with presumed ocular histoplasmosis or senile macular degeneration. Eyes selected for treatment must have a neovascular membrane between 200 to 250 microns from the center of the fovea. The natural history of these two diseases will also be studied, as well as the natural history and risks of development of drusen in Bruch's membrane.